Have a 77 BMW R100S mated to a Velorex 560. Both have mechanical drum brakes (rear) but I can't figure out how to attach the sidecar cable (has hook on the end) to my brake lever. Any ideas? Separate lever? If so, who makes them? Checked with Velorex USA with no success.

Hello Phil,
Sorry I do not have any photo on hand. I link here a photo out of Internet of a Jawa rig. http://www.ural.at/gf/IMG_0738.JPG
Behind the shift lever the triangle is a double lever of the foot brake that passes through the frame from the right side. The upper longer lever arm is for the back brake and the lower shorter lever is for the sidecar brake (cable goes around the front of the motor/the static cable receiver is part of the foot rest). Difference in length about 2 1/2" against 1 3/4" (length might be much shorter. relation should be S/C brake around 65% of back brake lever length) . That way they distribute the difference in needed force from back to sidecar brake.
The third flexible cable is for the brake light switch and the set screw for to adjust the brake pedal position.

So I assume if the brake had been assembled before on the same rig there is a cable rest and a second receiver hole in one of the brake levers at the foot brake.
Regards.
Sven